Nit: A function seems a little heavyweight here. This could just be:

```javascript
var centerOptions = Editor.BOUNDARY_CHECK_NORMAL;
if (isFindFirst && editor.isLineVisible(cursor.from().line)) {
    // no need to scroll if the line with the match is in view
    centerOptions = Editor.BOUNDARY_IGNORE_TOP;
}
```

Also, JSLint is complaining of a space at the end of the `return Editor.BOUNDARY_CHECK_NORMAL;` line.